Four people have been killed and dozens injured after a fire broke out at a building site in Tokyo.

The blaze hit an office building under construction in the city’s western suburbs on Thursday, leaving four dead and injuring about 40 others.

More than 70 ambulances and fire engines were sent to the scene.

Japan Fire
Smoke rises from the building under construction in Tama city (Kyodo News/AP)

Fire officials said more than 20 people were seriously injured.

The three-storey building in Tama city, which also has three underground floors, was near completion.

About 300 workers were at the site at the time of the fire. Television footage showed dozens of workers taking refuge in a nearby car park.

Japan Fire
Rescuers work at the site of a fire in Tama city, in Tokyo’s western suburbs (Kyodo News/AP)

The cause of the fire and the extent of the damage are being investigated, the fire department said.

The fire was believed to have started in construction materials on the bottom basement floor.

Fires at construction sites in Japan are not rare. In Tokyo alone, 100 to 200 fires are reported annually at buildings being built, repaired or renovated, according to the fire department.

Welding work, arson and smoking by construction workers are among the main causes.